Final answer:
The characteristics of an element's atoms, particularly the atomic number, determine the element's identity. Scientists use elemental analysis to find this information, which can also be applied to organize elements in the periodic table and identify the chemical composition of distant celestial bodies.
Step-by-step explanation:
The characteristics of an element's atoms are essential in determining the element's identity. One fundamental characteristic is the number of protons in the nucleus, which is known as the atomic number. This atomic number is unique to each element. For example, the atomic number for hydrogen is 1, for helium, it is 2, and for lithium, it is 3.
In determining the composition of a sample, such as seawater, scientists can use various analytical techniques. Elemental analysis is a procedure where the elemental composition of an unknown compound is analyzed, and the percentages of each element present are determined. This can lead to the empirical formula of the substance based on mole ratios.
Organizational efforts like Mendeleev's development of the periodic table have contributed to our understanding of the elements. The periodic table is based on the atomic number, providing a powerful tool for scientists to classify and manage information about the elements' properties. Astronomers and physicists extend these principles by analyzing the light spectra from celestial bodies to determine the chemical makeup of stars and galaxies.